High contrast transparent Ramsey fringes are observed using double microwave pulses interaction with the prepared atomic coherent state in a warm <sup>87</sup>Rb vapor with mixture buffer gases in a closed cell. The Ramsey fringes are generated by the pulsed technique, a strong coupling light pulse and a weak signal light pulse are applied to prepare the atomic coherent state, followed by the application of double microwave pulses to interact with the atomic coherent state. Afterwards, the light pulses are applied again with weaker intensity and detecting the signal transmission is delected. The central line of the transparent Ramsey fringes has narrow linewidth of 125 Hz and high contrast of 21%. The light shift is dramatically reduced since the interrogating process is not involved the light field, and the cavity pulling effect is negligible due to the low <i>Q</i> requirement, which is promising for building small, compact, and stable atomic clocks.
© 2013 Chinese Optics LettersPDF Article